Tool Kit Set,Complete Toolbox Sets,Toolbox Set,Tool Kit Case SUZHOU NEWSTAR HARDWARE CO.,LTD. , https://www.newstarhardware.com
Optimized arrangement of diamond abrasive grains: a laser arrangement technique and evaluation of its grinding force and wear characteristics
Abstract The manufacturing method of the traditional super-abrasive grinding wheel causes the abrasive particles to be consolidated on the surface of the grinding wheel in a random random arrangement. In order to solve these problems reasonably, a method for realizing on-demand three-dimensional controllable optimization of diamond micro-distribution cloth is introduced. Although this novel view of the production of abrasive grains on demand for diamond grinding wheels is only in the initial experimental stage, it has pointed the way for the development of micro-processing that was once neglected. Key words single crystal diamond polycrystalline diamond crystal optimized abrasive grain group In the 1950s, synthetic diamond has been widely used in cutting and grinding with the development of diamond technology using graphitization technology under high temperature and high pressure. The diamond abrasive has a high hardness (Knoop hardness close to 100 GPa) and a high thermal conductivity, which allows the grinding heat to be quickly transferred from the grinding zone, while also ensuring even when machining difficult materials. Ability to maintain high material removal rates. In addition, diamond has high wear resistance, which can meet the requirements of high dimensional stability of the grinding wheel surface, and can ensure the high shape and high precision requirements of the machined workpiece. In many high value-added grinding applications (such as aerospace, medical, automation), the need for careful machining of shape accuracy and surface quality combined with high productivity requires careful consideration of the specifications of the diamond wheel (eg abrasive size, bond strength). ) to meet production needs. Conventional superhard material (e.g., diamond) grinding wheels are typically produced by mixing diamond abrasive particles of selected characteristics and dimensions with a binder and then forming the mixture into the desired shape according to the model. These models (matrix) are usually characterized by random distribution of diamond crystals and different crystal pitches. In the case of abrasive particles distributed on the surface of a superhard grinding wheel, these abrasive particles are typically distributed in a scattered or inlaid state on the surface of the grinding wheel (ie, randomly distributed), and the abrasive grains are usually fixed on the grinding wheel by electroplating or sintering. . Crystals of ultra-hard materials currently used in commercial applications have anisotropy. The application of the above-mentioned grinding wheel manufacturing method results in significant morphological differences in the surface of the abrasive grain (grinding wheel). For example, lattice protrusions and crystal orientation changes. Thus, the difference in size and characteristics of all specific diamond abrasive grains is caused by the difference in lattice shape and measured size. Solving the problem of crystal size measurement (turning the three-dimensional irregular grain size into a uniform measurement size), the shape of the crystal will affect the measurement size of the grain, especially in the production of brittle abrasive grains that are widely used in the grinding industry. The grain shape will vary greatly. Included in the production of ultra-hard materials, the measured size distribution of the grains can generally be regarded as a Gaussion distribution, and any distribution will have a direct influence on the number of grains per carat of diamond. At the same time, the number of crystals per carat can be controlled on large diamonds, which is still unrealistic for smaller diamonds that dominate the grinding application. It is well known that the smaller the diamond size, the greater the grain strength in a particular production process. In precision grinding, it is important to select the position of the abrasive particles by selective positioning. Reasonable selection of the position of the abrasive particles allows the working area to have more abrasive particles with the same characteristics and can promote the outflow of the chips. Now using masking and electrolysis techniques, selective positioning of the abrasive particles can be successfully achieved, fixing the abrasive particles to the desired location on the surface of the grinding wheel; however, as the size of the abrasive grains of the grinding wheel decreases, these techniques show wasted time and no A realistic trend. Further research shows that the selection of abrasive grains with similar crystal plane structure can successfully improve the surface integrity of the grinding wheel, and at the same time, can further enhance the working efficiency of the entire grinding wheel. By reducing the difference in abrasive grain at the working height (bare height), the workload can be loaded more evenly on each abrasive grain, which significantly increases the grinding efficiency. Using various (alternative) techniques, the surface roughness of the workpiece can be successfully improved by reasonable selection of the abrasive grain position, and the chip removal is facilitated. Compared with the conventional grinding wheel which is in contact with the workpiece, the research shows that the grinding force is remarkable. decline. Along with the advancement of EDM technology, PCD tools produced by this method have been widely used in the field of microfabrication, and polycrystalline diamond materials are applied to tools with high precision machining. The diamond crystal structure is exposed by spark erosion of the PCD matrix. The method of making micro-grinding tools is already under study. The use of laser technology to machine holes in the PCD tool body improves the performance of micro-grinding, which improves the tool load and helps chip removal. As a high-performance cutting tool material, CVD diamond has been recognized and gradually used in a wide range of applications, but until now, no practical grinding tool material has been found. Today's CVD diamond synthesis technologies, such as microwave plasma chemical vapor deposition (MPCVD) and hot-wire chemical vapor deposition (HFCVD), can be used to synthesize various cylindrical-shaped single crystals and polycrystalline diamonds. Commercial CVD diamonds are used. As a base coating film (< 0.5 mm) or a thick film (0.5 to 2.5 mm) with a self-supporting structure, these structures are initially bonded to a suitable matrix material and removed in subsequent processing. In this method, discs with a diameter exceeding 100 mm can be produced. However, diamond films have been successfully used as coatings for cutting tools, and the use of films as coatings for grinding wheel substrates has also been reported. This view demonstrates that a significant increase in grinding performance can be successfully achieved by the specific arrangement of the abrasive particles coated on the base of the abrasive article, the exact position and the clear working height. A single single crystal diamond crystal (synthetic or natural) provides the possibility of producing a tool that can be used to arrange the grain as needed to suit the grinding conditions. The anisotropic nature of diamond results in unique mechanical and physical properties (such as wear resistance, strength, and friction factor) for different crystal faces or in different directions on the same crystal. Harder and softer crystal faces and their orientation can be used in tool design. It is reported that the cutting performance and wear characteristics of the edge of a single crystal diamond tool depend on the mutual positional relationship between the crystal direction and the load (cutting force) direction. At the same time, this relationship is also related to the grinding and cutting performance of the tool, and this relationship can also be applied to grinding. 1 Research Scope The effects of operating parameters (such as laser power density, feed rate) on the orderly alignment of diamond CVD films fabricated using ND:YAG pulsed lasers and the testing of these materials were investigated. If the alignment method is optimized, the performance of single crystal diamond and polycrystalline diamond is compared on a numerically controlled five-axis grinding machine. In addition, the wear characteristics of various arrangements of diamonds were tested using the TI-6AL-4V test, which is widely used in the high value-added grinding industry (medicine, aviation). In addition to the wear characteristics of a certain array of diamonds, the grinding forces and surface roughness achieved using single crystal diamond and polycrystalline diamond tools in the grinding test are compared. The idea of ​​ensuring optimal alignment has the potential to be applied in precision grinding. 2 The main idea of optimizing the arrangement of abrasive diamonds is to optimize the diamond abrasive grain arrangement by laser sintering technology, and to provide a new method for producing diamond tools in precision grinding. This method specifies the advantages of controllable abrasive grains and abrasive grain groups on the surface of the grinding wheel, with the same required dimensions, the same working height, and precise abrasive grain spacing. Furthermore, with the application of single crystal and polycrystalline diamond tools, it has become feasible to produce techniques with defined grain arrangement and orientation. The application of abrasive grain controllable diamond provides a new way to fundamentally solve the problems caused by traditional manufacturing techniques (arrangement of individual diamond abrasive grains). This technique is believed to provide a number of advantages in the precision grinding industry due to the high degree of shape repeatability and precise grain spacing when arranging diamond abrasive grains. The concept of the orderly arrangement of diamond abrasive grains is based on the following observations: (1) Micro-grains on a diamond-based tool are produced by grinding. However, due to the high hardness of diamond abrasive grains and their small size, the production methods of these arrangements may only be non-traditional techniques (such as laser sintering). (2) These abrasive particles will have different shapes (simulating the ideal abrasive grain arrangement), abrasive grain size (promoting heat dissipation or facilitating the application of cutting fluid) and arrangement direction (along the optimal arrangement of diamond grains) Processing to promote the ability to process special materials). In addition, these abrasive grain samples with optimized alignment directions can be produced from single crystal diamond (100 or 110 crystal faces of the initial plane of the finished sample). In addition, the abrasive particles can be symmetrically or staggered to meet the needs of different occasions. (3) The above diamond arrangement was tested using a commercial CVD diamond tool. In this test, the laser sintering technique was mainly used to control the arrangement of the effective abrasive grains. Diamond-based alignment techniques can be achieved by laser-spinning linear filling at fixed (0°) or variable angles (a series of continuous angles of 0°, 45°, 90° and 135 °). (4) Once the diamond abrasive grain arrangement pattern and geometric parameters are determined, we need to test their cutting or grinding capabilities. This makes it possible to determine the key geometric parameters of the abrasive grain-optimized arrangement associated with a certain machining (such as the surface texture required for the workpiece material). Based on the above viewpoints, this paper proposes the selection results of the practical method of selecting optimized abrasive grain arrangement. In the grinding simulation test, the cutting force and geometrical characteristics under different abrasive grain arrangements are evaluated. 3 Test procedure 3.1 Formation of diamond micro-array The ND:YAG pulsed laser emitter is assembled in a three-axis coupled laser processing center and has been used in the experiment of grinding grain arrangement by laser sintering of diamond. First, the main process of diamond abrasive grain arrangement is as follows: laser sintered linear filling with fixed or variable angles is performed. Initially, the test piece (5 mm × 10 mm × 0.5 mm) was ground with a polycrystalline CVD diamond tool, and a series of linear filling paths were selected to optimize the laser operating parameters, and the following output parameters can be controlled: the depth of the micro-groove, The continuity of the processed (graphitized particles) and the sharpness of the trimming (affecting the shape accuracy of the resulting crystal grains). With varying laser output power (30% to 90% of maximum power) and laser frequency (f = 30 to 50 Hz), various groove widths (0.040 to 0.060 mm) and depths (0.010 to 0.050) can be obtained. Mm). Second, once the optimized parameters are determined, multi-layer laser sintering on polycrystalline CVD diamonds is a good way to rapidly align abrasive grains, using HPHT diamond synthesis using multiple scan paths with continuous scan angles. Various shape features that can be found on the diamond crystal face, such as squares, triangles, and hexagons, and the like, and different shapes of abrasive grains in a specific square (length 0.1 to 0.6 mm and 0.1 to The 0.3 mm abrasive grain spacing is arranged on a polycrystalline diamond matrix (5 mm × 10 mm × 0.5 mm). Third, the use of laser sintering to optimize the arrangement technology, and the two types of diamond-grained diamond cutters (polycrystalline and single crystal diamond) pre-cut bars produced by ElementSix. CVD-MY has a polycrystalline cylindrical crystal structure, and CVD-MCC is a single crystal structure, and its structural features are similar to the 100 or 110 crystal plane structure on the polished surface of the sample. A diamond abrasive having characteristics of different crystals (single crystal or polycrystalline 100 or 110) was produced, and the magnitude of the grinding force on each of the abrasive grains was evaluated. In this arrangement, the abrasive grain group has a defined square crystal with a margin of 0.1 mm and 80 abrasive grains per cubic meter of abrasive grain group. This allows up to eight abrasive grains to be staggered across the 0.8 mm diamond abrasive section to form the desired direction of the grinding path required for this arrangement. After laser sintering single crystal or polycrystalline diamond, the workpiece was immersed in aqua regia for 2 h, and then ultrasonically cleaned in deionized water for 15 min to remove residual graphite on the surface of the workpiece. Once this laser sintering technique was successfully applied to CVD diamond, the shape of the arrangement was examined using a fiber-optic digital microscope and then evaluated in three dimensions using a CLT1000 surface texture analyzer. 3.2 Grinding test The simulated grinding test is carried out using CVD diamond raw materials with a specific optimized abrasive grain arrangement (for example, 100 or 110) to evaluate the cutting ability under different abrasive grain arrangements. Grinding the tube Ti-6AL-4V with the following cutting parameters on a self-supporting 08 mm × 0.8 mm × 5 mm CVD diamond substrate: αp = 0.003 mm, v = 20 m/s, vf = 300 mm/min, Houghton 3380 coolant supply. Carefully select these cutting parameters to ensure that the average pressure on each abrasive grain does not exceed 0.25 N to avoid early fracture and potential grinding burns. A simulated grinding test was performed on a five-axis Makino A55 machining center to verify the integrity (reliability) of the abrasive grain arrangement (using an optical scanning electron microscope) with intermittent failure and to record the wear and fracture characteristics. In addition, the triaxial dynamometer is connected to the charge amplifier, and the cutting force parameters are collected at a sampling rate of 10 KHz using a data acquisition card and a PC; the diamonds of three abrasive grain arrangements are compared (CVD-M, CVD-MCC100) , CVD-MCC110) Main cutting force. The roughness of the surface of the Ti-6AL-4V workpiece was measured by a three-dimensional surface roughness meter after each simulated grinding test. 4 Results and analysis       4.1 Laser Measurement and Diamond Abrasive Group Measurement To solve the technical problem of using laser sintering to synthesize diamond abrasive grains and abrasive grain groups, it is necessary to select the correct operating parameters. The parameters of laser-sintered CVD diamond have been limited to a small range to avoid surface defects as described below. (1) Edge effect of diamond laser sintering. These defects include the edge of the blade that does not change sharply due to the laser beam eroding the diamond matrix. When processing the surface, these soft defects are usually set too low at the laser density power (P=4.75 to 9.95 W CM-2×106), and the beam speed (V=500 to 600 mm/s) is set too. High and no local temperature is too low. (2) Laser sintering surface burns. This defect consists of a round, highly graphitized sintered surface that results in a reduced crystal grain clarity. However, in more severe environments, the size of the abrasive particles can be significantly reduced due to the effects of excessive graphitization. This type of burn is more likely to occur when the laser power density is too low and the beam scanning speed is too low. (3) Unstable penetration depth. Due to the unstable depth of penetration, the working height of the diamond abrasive grain group is inconsistent, which in turn reduces the working efficiency of the diamond tool. Therefore, the occurrence of such defects should be avoided. This type of defect is more likely to occur when the laser beam moves too fast, the power density is too high, and the frequency is too low. The cause of this defect is related to the fact that there is no or only a small amount of abrasive grain superposition in the feed direction. If the operating parameters of the laser sintering optimized abrasive grain arrangement are optimized, it is possible to generate a plurality of abrasive grain groups of polygonal, rectangular and triangular patterns on the polycrystalline diamond substrate using a multi-channel continuously varying scanning angle. After the abrasive particles and abrasive populations were successfully placed on the CVD diamond substrate, the size and geometric accuracy of the abrasive particles and abrasive populations were analyzed using an optical surface texture analyzer. From the above results, we can notice that the abrasive grains of different shapes have no significant difference in size and geometric accuracy on the diamond abrasive grain groups of different modes. This laser sintering method for arranging diamond abrasive grains needs to be further developed to increase the precision of the abrasive grain group to achieve the following objectives: to increase the sharpness of the abrasive grain sharpening blade by using smaller size abrasive grains and higher pulse frequency. And geometric accuracy, reducing the shedding of the abrasive particles, especially on the main cutting edge to fully tilt the laser beam to make up for this defect. Laser arranging technology has proven to be a reliable method for arranging diamond abrasive particles. At this stage, the technology has been successfully applied to arrange diamond abrasive grains on polycrystalline diamond and optimized crystal orientation single crystal CVD diamond. However, the number of square abrasive particles needs further research to ensure smooth grinding tests. 4.2 Grinding test results It is well known that although the optimization of the abrasive grain spacing and the shape of the abrasive grain group is not sufficient, the simulated grinding test can carry out some preliminary explorations: 1. Abrasive grain processing Working performance; Second, the cutting ability of a specific abrasive grain in different crystal directions. For polycrystalline diamonds with three defined shape abrasive grain groups and single crystal diamonds with specific crystal orientations, the evaluation of the above various properties needs to focus on the following aspects: in the same cutting parameters test The average radius of the obtained abrasive grain group, the main cutting force, and the abrasion of the abrasive grain in the tool durability. Optical electron microscopy analysis showed that the wear and damage of the abrasive grain group changed significantly after the cutting length reached more than 100 m. Diamond abrasive grains on polycrystalline CVD diamond show significant cracks on the main cutting edge, and wear marks appear on the ground contact surface. In this case, more material to be processed adheres to the effective grinding edge of the abrasive particles, which is in sharp contrast to the case of using single crystal CVD diamond. However, single crystal CVD diamond abrasive grains do not show significant cracks, and their wear characteristics are significantly different in different crystal plane directions. (110) The abrasive grains in the crystal plane direction will have obvious pitting on the contact surface, and the unevenness will appear on the main cutting edge. Conversely, in the contact plane of the diamond abrasive grains in the (100) crystal plane direction, significant ripples appear in the grinding direction, and the main cutting edges are also slightly discolored. The early wear crack of polycrystalline diamond abrasive grains is caused by its structural strength (the tensile strength of CVD-M reaches 400-800 Mpa and the tensile strength of CVD-MCC reaches 2,000-3 000 MPa). In applications, cracks in the abrasive grain of this arrangement on the main cutting edge can cause early damage to the tool. In this grinding simulation test, the surface of the abrasive grain in the direction of the 100 crystal plane is more pronounced than that of the abrasive grain in the direction of the 110 crystal plane. More early studies have shown that diamonds in the 100-plane orientation are softer than diamonds in the 110-plane orientation. However, the diamond in the 100-plane orientation also exhibits relatively high thermal stability. This may explain that if there is a significant heat loss, thermal damage tends to occur on the diamond surface in the direction of the 100 crystal faces. Through the study of the wear resistance of the crystals of each layer related to the azimuth angle, it is found that the diamond of the 100 crystal plane of the 100 crystal orientation is higher than the diamond of the crystal plane of the 100 crystal plane 110, and the former exhibits a higher wear rate. The special operating parameters, through continuous experimentation, found that the abrasive grains of the previous arrangement showed higher wear. In the case of oxidation at a temperature of 650 ° C, the phenomenon of titanium oxide on the surface of the diamond can explain the phenomenon of surface pitting on the 110 grain upward abrasive grain group. In particular, the discoloration of the main cutting edge indicates that hot cracks have appeared on the surface; however, for the problem of surface titanium carbide formation, no further research has been conducted and the surface temperature has not been measured in the test. In these basic studies on the grinding performance of CVD diamond abrasive grains, it is mainly through design tests to observe early wear phenomena. Then, through further tests, the wear characteristics of the abrasive grain group become more pronounced. A closer look at the abrasive particles makes it easier to understand some of the tiny phenomena that occur on the cutting edge of the tool. Therefore, it can be understood that the performance of the abrasive grains composed of different structural diamonds is different. The magnitude of the detected force signal can account for the overall performance of the abrasive particles in the simulated grinding test. In the grinding process, there is no significant difference in the average circumferential force required to use the single crystal diamond and the 100 crystal orientation polycrystalline diamond. It is found that the circumferential force required for the 110 crystal orientation diamond tool is slightly smaller; The measured circumferential forces of the diamond tools in the form of a layout may partially overlap, and therefore, the circumferential forces required for them may be considered to be substantially the same. However, it can be observed. The cutting forces of single crystal and polycrystalline diamond tools can vary significantly. The crack and side wear of the main cutting edge of the polycrystalline diamond tool can explain this result, and the crack of the main cutting edge of the single crystal diamond tool is not obvious. At the same time, the main cutting forces on the single crystal diamond tool are similar, and the higher cutting force in the 100 crystal direction produces abrasive grains having a wave wear pattern in the grinding direction in the grinding direction. Therefore, it is possible to make the tool surface have more minute abrasive grains that can be used for grinding during grinding. The roughness of the surface of the Ti-6Al-4 workpiece polished by three diamond tools was as follows: Ra = 0.31 μm CVD-M; Ra = 0.60 μm CVD-MCC (100); Ra = 0.67 μm CVD-MCC (110). The roughness of the CVD-MCC (100) and the CVD-MCC (110) polycrystalline diamond is similar. Better surface roughness can be obtained with polycrystalline diamond. This phenomenon can be explained by the fact that early cracks in polycrystalline diamond abrasive grains produce sharper cutting conditions. It is well known that tools that do not optimize the scanning angle to grind the surface of the highly plastic Ti-6Al-4V workpiece have no high material removal rate. This method proves that the abrasive grains produced by laser sintering are arranged in a certain way. The tool can be used in grinding. However, there is a desire to improve the roughness of the workpiece by utilizing a more efficient scanning angle on the cutting edge to improve the roughness of the workpiece. However, the use of an optimized scanning angle to produce a tool in which the abrasive particles are arranged in a certain manner, thereby increasing the surface roughness of the machine, has the risk of reducing the strength. 5 Optimizing the application prospects of abrasive grain diamond cutting tools These basic researches mainly propose two novel methods that have attracted the attention of the manufacturing industry. These two methods have great potential in future technological development. This paper specifies the ability to produce abrasive particles on a CVD diamond substrate using a laser sintering method to distribute the abrasive particles in a certain manner. So this way you can improve tool performance. At the same time, the results of simulated grinding test show that the optimized grinding performance can be improved by using the optimized abrasive grain arrangement. From this basic finding, we can get the following conclusions: We can use diamond arrangement technology to manufacture single-layer diamond abrasive grinding wheel. On the grinding wheel, the abrasive particles are distributed on the basic surface of the grinding wheel as needed. Also this technique can be applied to the manufacture of grinding wheels in a multi-layer abrasive grain arrangement in which abrasive particles can be implanted in the grinding wheel matrix. In this case, the laser sintering technique can be used to arrange the abrasive grains on the CVD diamond material or the disk-shaped raw material according to certain requirements. The diamond abrasive grain arrangement technique can arrange the abrasive grains in a certain crystallographic direction on a specific plane of the CVD diamond plate, bar or larger particles. The surface of the curved wheel needs to set the radius of the abrasive to meet the requirements of the shape and arrangement direction of the abrasive. This provides the possibility of producing tools for surface grinding. However, the 100 and 110 crystal orientations have little difference in tool size performance, making it possible to produce curved abrasive cluster diamond tools. This is in the opposite direction to the direction of the diamond material used at the time. Each grain has a progressively different crystal orientation. This also offers the possibility of producing ultra-high precision tools. 6 Conclusion This paper first proposed a method for optimizing the production of film-based diamond tools by abrasive grain arrangement, and tested the cutting ability of the tool. Using crystallographic methods, laser sintering of individual abrasive particles and multi-linear arrays of abrasive particles, CVD diamonds in single crystal 110 and 100 crystals have been largely successful in achieving a higher degree of overlap of abrasive particles. The abrasive grain group is superior in size to the abrasive grains obtained by multi-linear laser grinding. By using the pattern arrangement formed by such a laser, a series of abrasive grains that can be used for testing and a group of abrasive grains controllable by laser sintering on the film diamond matrix can be produced. This technology successfully achieves a variety of abrasive grains with a uniform arrangement. Performance evaluations for optimizing the abrasive grain arrangement of the diamond tool show that the grain arrangement affects the output parameters of the grinding. The grinding wheel optimized by the abrasive grain arrangement can significantly reduce the main cutting force, and the wear of the abrasive grinding edge is also reduced. At the same time, these basic researches focus on how to use crystallographic methods to obtain diamond tools with optimized abrasive grain arrangement and the performance of the tool in processing difficult-to-machine materials. There is still no research on abrasive grain arrangement and abrasive grain group pattern. progress. It is conceivable that a particular processing solution requires a specific abrasive grain arrangement, abrasive size, shape, and spacing. Note: This article is based on: Preferentially oriented diamond micro-arrays : A laser pat terning technique and preliminary evaluation of their cutting forces and wear characteristics.